1. Field of the Invention
The present invention relates in general to a water operated control apparatus and method for operating pneumatically responsive means, which may be associated with controlled devices, such as a pneumatically operated diaphragm means which may be associated with a water valve, electrical contacts or mechanical mechanisms, and which act in response to the level of moisture available at a given location and sensed by means of an associated moisture sensing apparatus.
2. Description of the Prior Art
Various types of irrigation control devices have been developed heretofore for irrigating lawns, golf courses, agricultural fields and even individual trees or plants which may be potted or planted. In general, the larger irrigation areas have been watered through sprinkler systems which are controlled by timer operated control devices. Individual plants or trees have been irrigated manually or by a timed and controlled stream or drip of water. Watering or irrigating by these and other prior methods have generally been in response to a predetermined timed sequence of watering operations which are not necessarily compatible with the actual need for water in the area being irrigated due to the change of climatic conditions independent of the mere passage of time.
There is a need in the art for apparatus and methods of irrigating both large and small planted areas, whether they be a farm field or a potted planting, wherein the amount of water supplied, and the timing of such supply, is correlated to the actual need for water in such location. In my prior application for U.S. Letters Patent Ser. No. 190,528 filed Oct. 19, 1971 and now U.S. Pat. No. 3,827,459 entitled "Water Powered Drive for Automatic Controllers" by way of example, I disclosed automatic irrigation control apparatus which is activated in a timed sequence of operation regardless of the actual moisture condition of the soil in the location of sprinklers controlled by the apparatus. I have recognized that it would be desirable to have some means for either starting, or not starting, the irrigation control apparatus of my prior application Ser. No. 190,528 in response to the presence or absence of a sufficient amount of moisture in the soil to be irrigated by the sprinkler system associated with the apparatus. I have also recognized that it would be desirable to provide such means in a relatively inexpensive manner and that it should preferably be water powered since a source of water is generally available to irrigation control apparatus, whereas electrical power may not.
It has also been known in the prior art that various devices can be used for determining the level of moisture in a given location in order to determine whether irrigation is required or not. One way would be to take core samples of the dirt in a location and testing each for its moisture content. However, it is also known that certain materials may pass air therethrough when dry but prevent the passage of air therethrough when saturated with water. Such moisture sensitive air valves, heretofore known in the art, comprise porous ceramic or plastic materials which have the ability to pass air or not, depending upon the amount of their water saturation. The measure of the ability of such materials or devices to pass air therethrough is generally referred to in the art as the "bubbling pressure", i.e., the pressure required for air to pass through the wetted material which is related to the pore size of the material.